1. Field of the Invention
This invention relates to a light beam modulating and deflecting system used to record and read out information by scanning a scanning surface with a light beam such as a laser beam, and more particularly to a light beam modulating and deflecting system which has at least one light source (semiconductor laser, light emitting diode or the like) mounted on a rotating body and which simultaneously carries out both modulation and deflection of the light beam emitted from the light source rotating together with the rotating body, wherein the light beam is deflected through the rotation of the rotating body and, at the same time, modulated by means of the drive current for the light source.
2. Description of the Prior Art
Laser sources can generate light beams exhibiting high spatial interference and a high spectral line brightness that cannot be obtained with the other types of light sources. By virtue of these advantages, laser sources are used for many optical read out and recording systems. For example, the laser sources are used for read out systems such as in facsimile transmitters, automatic readers for label bar codes, and film flaw detectors. The laser sources are also used for recording systems such as in video disc recorders and facsimile receivers. In the past, these laser-based systems employed mainly the gas lasers such as He-Ne, He-Cd and Ar lasers. However, the gas laser sources are intrinsically large in size and, in addition, necessitate additional light scanners and light modulators for deflecting and modulating the light beam during scanning with the light beam. Consequently, such systems using gas lasers are, in general, large in size and expensive. Thus, recently, semiconductor laser systems which are small and exhibit high efficiency have come into increasingly wide use. One example of such a system is that disclosed in Japanese patent application No. 54(1979)-84224 in which a semiconductor laser source is rotated to form linear scanning lines.
The semiconductor laser scanning system described in Japanese patent application No. 54(1979)-84224 is small in size and inexpensive, and yet can modulate and deflect the light beam without necessitating additional devices. In this system, electric power is supplied to the rotating light source by use of brushes. However, semiconductor laser sources are easily damaged by electric shocks and, therefore, break due to the electrical noise caused by the brushes. This conventional system is also disadvantageous in that it cannot be used for long periods of time because of wearing of the brushes.